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| Titel |
The atmospheric HCHO budget at coastal East and West Antarctica: Impact of photochemical productions and snow emissions |
| VerfasserIn |
Michel Legrand, Susanne Preunkert, Guillaume Pépy, Bruno Jourdain |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080013
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| Zusammenfassung |
| HCHO year-round records are now available at three coastal Antarctic sites, Neumayer and
Halley in the Weddell Sea region and Dumont d’Urville in Terre Adélie, revealing a similar
seasonal pattern with winter minima and summer maxima. However, absolute values
significantly differ from site to site, during summer and winter. Monthly summer means
exceed 450 pptv at NM, whereas a HCHO maximum of 130 pptv is observed at HA. Summer
HCHO levels at DDU are similar to those at HA although higher levels were expected in
relation with a methane oxidation being promoted by a 5 times higher level of OH at DDU
than at HA. On the other hand, to match observations at NM and HA, snow emissions have to
be considered whereas photochemical HCHO sources and sinks alone seem to explain
observations at DDU.
With the aim to draw a more comprehensive picture of the HCHO budget at coastal
Antarctica we reexamine and discuss the three records using 0-D and 2-D calculations. In
summer, the gas phase photochemistry is at all sites dominated by the CH4 oxidation, well
before the oxidation of DMS and light alkenes. The CH4 oxidation chemistry is some three
times more efficient in producing HCHO at DDU than at the two other sites because of more
rich oxidant air masses coming from the Antarctic plateau reach DDU. The halogen
chemistry, even being more important in relation with much sea-ice at HA and NM than at
DDU, remains a weak HCHO sink. HCHO snow emissions represent an important
contribution at the two Weddell Sea sites whereas they contribute only weakly at
DDU.
Although they are probably of similar strength around the three sites, the far thinner
atmospheric boundary layer at HA (and even more at NM) compared to DDU permit an
efficient accumulation of HCHO emitted by this surface source.
In addition these coastal Antarctic data sets will be opposed to HCHO mixing ratios
and snow fluxes obtained at inland Antarctica (Dome C) within the framework
of the OPALE (Oxidant Production over Antarctic Land and its Export) project. |
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